&#34;teflon&#34; faced shoe for the pressure foot of a sewing machine or the like



July 11, 1961 v' u c. G. JoA 2,991,739

TEELoN EACED SEoE EoR THE PRESSURE FooT 0E A SEWING MACHINE oR THE LIKEFiled Dec. 2, 1957 INVENTOR.

United State 2,991,739 TEFLON FACED SHOE FOR THE PRESSURE FOOT F 'ASEWING MACE OR THE LIKE Curt George Joa, Ocean Ridge, Fla. (Box 1121,Boynton Beach, Fla.) Filed Dec. 2, 1957, Ser. No. 700,039 Claims. (Cl.112`235) This invention relates to a Teflon faced shoe for the pressurefoot of a sewing machine or the like.

Manufacturers of upholstered goods, and others having occasion to usefabrics with high frictional surfaces, have encountered for many yearsdiiiiculties in handling such materials with conventional sewingmachines. One plant using fty-iive sewing machines of a well-knownmanufacturer has, on numerous occasions, had sewing machine engineerscome to the plant in an effort to solve frictional problems. The metalshoes with which the machines are equipped are polished as highly as ispossible. The engineers suggested that these surfaces be treated withwaxes, including silicone wax. While these solved, in part, the problemof high friction, the waxes, when dried, became powdery and created anuisance and a hazard to the eyes of the operator.

Other eiorts to solve the problem involved incorporating ball bearings,wires and the like in the foot and various arrangements for driving thefoot in a manner which it was hoped would relieve the frictional contactof the foot with the work.

After many months of time and thousands of dollars of expense, asolution was found in the provision of a plastic shoe attachment for thesewing machine foot to provide a surface of Teflon, the chemical name ofwhich is tetrafluoroethylene polymer. It is not desired to limit theinvention to the particular material bearing the trade mark Teflon sinceother materials of equivalent characteristics may be substituted. Suchmaterials completely solve the problem of friction and their use doesnot involve any nuisance or impair in any manner the health of theoperator. Such materials are somewhat more subject to wear than themetal foot and hence provision has had to be made facilitatingreplacement of the shoe sole from time to time. The toe portion of theshoe can be permanently fixed to the fitting and has so little Wear thatreplacement has not been found to be necessary.

While the invention consists primarily in the use of Teflon orequivalent material to provide a sole surface for the pressure foot, thematerial is not involved in that aspect of the invention Which concernsthe particular means by which the sole is interchangeably applied on aWay with which the foot is provided, being locked in place by aretractable pin, a special fitting being used to retract the pin and toslide a substitute shoe sole into position, the worn sole being ejectedas the new sole is applied. Y

In the drawings:

FIG. 1 is a view in side elevation of a sewing machine foot equippedwith a shoe in accordance with the present invention.

FIG. 2 shows the parts in front elevation.

FIG. 3 is a view partially in side elevation and partially in sectionshowing the pressure foot `and Worn shoe and showing in side elevationthe applying tool and substitute shoe about to displace the worn shoefrom t-he foot.

FIG. 4 is a view similar to FIG. 3 in which the tool and substitute shoeare also shown in section and in the course of displacing the used solemember.

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FIG. 5 is a view showing in perspective the relatively separatedpressure foot and a substitute sole member.

FIG. 6 is a view taken in transverse section on the' plane 6 6 of FIG. 3

FIG. 7 is a fragmentary detail view in plan of a latch pin retractingdowel forming a part of the shoe replacing tool.

Except for the provision of the toe and sole plate members which aremade of plastic, the pressure foot organization of the sewing machineremains unchanged. Conventionally this comprises a shank 10. In theparticular device illustrated, the fitting 11 at the lower end of theshank is provided with two separate carriers 12 and 13 which arepositioned side by side and pivoted to the fitting 11 by a common pintleextending through the fitting at 14. The respective shoes 15 and 16 arepivoted to the carriers 12 and 13 upon individual pintles such as thatshown at 17 in FIGS. 1 and 3. Springs such as that shown in dotted linesat 18 are disposed behind the pintle 14, Where they tend to elevate thesaid ends of the carriers 12 and 13 into contact with an equalizinglever 20 which is pivoted on the shoulder bolt 21 so that any tendencyof the Work to raise one of the shoes will bring about a lowering of theother, thus enabling the two shoes to oat side by side upon the work.

In accordances with the present invention, each of the shoes is beveledat its forward end in the manner shown at 22 in FIG. l and FIG. 3. Tothis beveled forward face is fixed the Teilen toe portion 24 of the shoewith which the pressure foot is provided in accordance with the presentinvention. The toe portion may be cemented or otherwise permanentlyfixed to the foot.

Each sole portion 25 has a dovetailed slot at 26 to receive thecomplementary way 27 provided on the under surface of the foot anddesirably extended at 270 on theV under surface of the toe member 24 asshown in FIG. 3 and FIG. 5.

Extending into the front of the shoe through the toe l portion is alongitudinal bore 30 intersected by an upright counterbore at 31 spannedby a pin 32 which provides a seat for compression spring 33. Biaseddownwardly by the spring 33 is the head 34 of a lock pin 35 which isguided in a hole 36 in the foot 15 and urged into the corresponding hole37 in the shoe 25 as a means of latching the shoe to the foot duringuse.

In order to replace the shoe it is only necessary to raise the latch pin35 su'iciently to clear the shoe 25, whereupon the shoe will readilyslide either forwardly or rearwardly along the way 27 until free of thefoot.

To facilitate replacement without loss of time by sewing machineoperators who may have little or no mechanical skills, I providethe-tool shown in FIGS. 3 and 4. This tool comprises a body member 40-Which is provided with a way at 41 identical with that of the foot 15 toconstitute a forward extension thereof. the tool body 40 is mounted asubstitute foot 250 engaged by the thrust slide V42 reciprocable alongthe tool body 40 subject to the control of the handle 43. The

will enga-ge beneath the head 34 of the latch pin to raise ,I

the latch pin in its counterbore 31 against the bias of spring 33. This-frees the shoe 25 so that the advance of replacement shoe 250 can slideshoe 25 from the foot.

Figure 4 shows shoe 25 partially displaced and shoe 250 lPatented I Julyll, 1961y Upon the way 41 of 3 has advanced into interlocking engagementwith the Way 27 of the foot.

When the slide 42 reaches the limit of movement permitted it, the socket37 in the replacement shoe 250 will register with the latch pin 35,50that on Withdrawal of the dowel, the bias of spring 33`will engage thelatch pin with the replacement shoe to tix this securely tothe foot.

As'positioned on the foot, the curved lower surface at the forward endof the Teflon shoe will be continued by the curved forward end surface49 of the toe member 24 to guide the work smoothly beneathV the foot.

The particular material substantially eliminates excessivefrictionbetween the foot and the work, regardless of the character of the workmaterial. Notwithstanding that the Teflon is susceptible to wear,replacement becomes a simple matter in view of the construction of theshoe and the tool as above described.

I claim:

1. The combination with a sewing machine pressure foot member elongatedfrom front to rear in the direction of relative movement l'between thefoot and the Work upon which the sewing machine is operating, and adetachable sole member therefor having an elongation corresponding tothat of the foot and underlying the foot substantially throughout itslength, the sole member providing substantially the entire workcontacting surface of said foot, one of said membershaving `a way ofless width than the sole member and disposed above and eX- tendinglongitudinally of said surface and the other of said members having abearing surface complementary thereto, one of said members having a lockbolt for which the other is provided with a socket adapted to receivethe bolt, the engagement of the bolt in the socket releasably securingthe sole member against movement along the way respecting the footmember.

2. The combination set -forth in claim-l in which the foot member has atleast a surface portion of Teflon 3. The combination'with a sewingmachine pressure foot elongated from front to rear of the sewingmachinein the normal direction of relative movement between the foot andwork upon which the sewing machine is operating and provided with agenerally horizontal longitudinally extending way of dovetail crosssection, of a workengaging sole member having a dovetail bearingcomplementary to that of the way and slidable longitudinally of thefoot, and a pin retractably mounted in the foot and for which the solemember is provided with a socket, said pin being normally biased to andengaged in the socket solely by its bias to secure the sole memberagainst displacement respecting the foot.

4. The combination with a sewing machine foot member and a sole membertherefor mechanically separable i from the foot member byslidingpmovement from therebeneath, one of said members being providedwith a dovetail way and the other with a complementary bearing surfacefor accommodating `such slide movement, the foot member being providedwith a tool-receiving socket and with a retractable pin disposedtransversely with respect to the socket, and normally in lockingengagement with the sole, and having a shouldered portion exposed toengagement by a tool inserted into the socket, whereby when a tool is inthe socket said pin is retracted to free the sole member fordisplacement from the foot member along said way.

5. The combination with an elongated sewing machine foot provided withIa longitudinal bore and a I,dovetailed way therebeneath, of a solemember in slidably detachable connection with the foot and having abearing surface complementary to the way, the foot being provided with ahole vertically intersecting the bore and the sole member having asocket normally registering with said hole, a pin retractably mounted inthe hole and having means biasing it into normal engagement in thesocket to restrain the sole member against sliding movement along theway, the pin being shouldered within said bore.

6. A tool for the replacement of a sewing machine pressure foot solemember, the tool comprising means for supporting and longitudinallypropelling a substitute sole member and a dowel projectinglongitudinally above the level of the supporting means and provided witha forward end providing a camming surface the supporting meanscomprising a way of dovetail cross section and the propelling meanscomprising a slide, the dowel being adapted to position the way of thesupporting means with respect to the pressure foot while the slidepropels the substitute sole member along the way.

7. As a new article of manufacture, a sewing machine pressure foot solemember comprising a plastic part having a longitudinally elongatedundercut bearing surface constituting a way and having a work-engagingbottom face curving upwardly at one end toward the level of said bearingsurface.

8. The combination with a sewing machine pressure foot elongated fromfront to rear of the machine iny the direction of normal relativemovement between the foot and the work upon which the sewing machine isoperating, said foot being provided with a generally horizontal way ofdovetail cross section extending longitudinally 'of the foot in saidfront to rear direction; of a work engaging sole member having a`dovetail bearing complementary to that of the way and provided with alower surface of Teflom a pin retractably mounted in the foot and biaseddownwardly and for which the sole member is provided with a socket, thepin being freely movable in opposition to its bias for release from thesocket of the sole member and having a head exposed for camming actionto effect movement of the pin in a direction to release the sole member,said pressure foot having tool guiding means for guiding a pinretracting tool upon a path such as to withdraw the pin from the socket.

9. The device of claim 8 in which the pressure foot has a way extendinglongitudinally from front to rear thereof and constituting the aforesaidtool guiding means, the head of said pin being disposed proximateV saidway in the path of a tool guided by said way.

10. In a sewing machine having a pressure foot elongated from front torear in the direction of normal relative movement between the foot andthe work upon which the sewing machine is operating, said foot having adetachable shoe extending longitudinally of said elongated foot andhaving a sliding front to rea'r connection therewith and adapted to bedisplaced by a tool having a dowel iior which the foot has. alongitudinal socket; the combination withsaid longitudinally socketedfoot and slidably detachable shoe, of a pin having a shoulder within thesocket and spaced fromthe bottom thereof, said pin being normally biaseddownwardly and said shoe having a portion normally engaged by said pinto restrain the Y shoe against displacement respecting the foot, theshoulder of the pin being engageable by the 'said dowel upon itsinsertion in the socket of the shoe for lifting the pin in opposition toits bias preliminary to thel functioning of said tool upon the solemember.

References Cited in the tile of this patent UNITED STATES PATENTS 47,978Peterson T- May 30, 1865 765,884 1 Dormandy July 26, 1904 770,008Holderman Sept. 13, 1904 857,431 Allan June 18, 1907 2,674,036 ButlinApr. 6, 1954 2,706,460 Grossman Apr. 19, 1955 2,750,697 Jacobson June19, A1956 '2,814,266 Marshall Nov. 26, 1957 FOREIGN PATENTS 654,308Germany Dec. 16, 1937 OTHER REFERENCES Dupont Product EngineeringBulletin (3), Article on Teilen pages 1-3 inclusive, 1955, on tile inDivision 60.

